Spatial light modulators (SLMs) are transducers that modulate an incident beam of light in a spatial pattern in response to an optical or electrical input. The incident light beam may be modulated in phase, intensity, polarization, or direction. This modulation may be accomplished through the use of a variety of materials exhibiting magneto-optic, electro-optic, or elastic properties. SLMs have many applications, including optical information processing, display systems, and electrostatic printing.
Spatial light modulators in projection displays that have micromirror arrays generally have plate portions for reflecting light and hinge portions for allowing movement of the plate portions, such as in response to an electrostatic attraction from an adjacent electrode. The plate portions can be rotated between ON and OFF positions, where light is directed through projection optics from ON micromirrors onto a target. The micromirrors can be operated in analog mode or in digital pulse width modulation mode in order to obtain gray scale at each micromirror location. A color sequencing device, such as a prism or color wheel, can be used to create a color image—or dedicated spatial light modulators for individual colors can be used.